Canada to provide satellite images this week
China has been asking foreign governments to help provide satellite images of the earthquake zone but so far only Canada has agreed to schedule a flyover on Friday, researchers of the nation's space agency said.
Researchers have been able to gather data from two Chinese-owned civilian earth observation satellites streaming down to the Centre for Resource Satellite Data and Applications (Cresda), the Remote Sensing Satellite Ground Station (RSSG) and other space agencies. However, their quality was so poor that scientists could hardly use them to determine the scale of the damage, an RSSG researcher said yesterday.
'We have barely slept since Monday night and tried to find out as much detail as possible. Like every ordinary Chinese, we are desperate to see what has happened down there and what is going on right now,' the researcher said.
'But there was a cloud right above Wenchuan so huge and thick that neither our camera nor infrared devices could penetrate. Our view has been completely blocked. [On Monday] we submitted requests to Canada and the European Union to use their satellites which are equipped with high definition synthetic aperture radar (Sar) that can see through the clouds.
'Today we received a reply from Canada that the only available scanning slot it can offer is on Friday ... there is nothing we can do but wait.'
Cresda has also appealed to overseas space agencies for help but so far received no reply, a researcher at the centre said.
Sar is the only satellite imagery that can be acquired at any time of day and in adverse weather. It takes advantage of the long-range capabilities of radar and the complex information processing capability of modern digital electronics to provide high-resolution imagery.
A Sar satellite weighs many tonnes and costs nearly US$1 billion, a leading mainland satellite scientist said.
He said China had an Sar satellite valued at nearly 2 billion yuan, but its quality may be too poor to be of any use to the rescue effort.
'The Canadian satellite has a very good quality Sar for civilian purposes but they may need time to manoeuvre to fly above Sichuan. Reconnaissance aircraft may get in place earlier and obtain some better images.'